Thanks!
Actually, that brings up an interesting behaviour that made me shake my head at first...perhaps you can explain (not critical--don't worry about it).
The CD I have clearly says Vectorworks 10.1: and Foundation, Architect,Landmark, Mechanical and Spotlight are checked off (presumably to indicate they are present on the disk, which they are).
The exact error I got when trying to apply the individual modules is that the module installs don't match the current version (this was before I updated to 10.1.2).
I'm wondering if the disk has a 10.1 installer for VW and 10.0 installers for the extras, and they're barfing on that mis-match.
Anyway, I will get in touch with our vendor and find out what happened....thanks for your help!
Oliver